JP6992792B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire in which the tread reinforcing element is made of a thermoplastic resin.

Conventional pneumatic tires have secured the basic characteristics of tires by using vulcanized rubber and cord materials such as organic fibers and steel fibers. However, vulcanized rubber has a problem that it is difficult to recycle the material. In addition, the use of cord materials, especially carcass cords, has the problem of complicating the manufacturing process and increasing manufacturing costs.

Therefore, Patent Document 1 below proposes a carcassless tire in which a tire skeleton member is made of a thermoplastic resin. The tire skeleton member includes a pair of bead portions, a pair of side portions extending from the pair of bead portions, and a crown portion connecting the pair of side portions. A tread made of vulcanized rubber is arranged on the crown portion.

Japanese Patent No. 6138695

However, in the tire proposed above, a cord layer in which a reinforcing cord such as a steel cord is spirally wound is used as a tread reinforcing element.

Therefore, when manufacturing a tire, a step of winding a reinforcing cord on the outer peripheral surface of the tire skeleton member is required, which causes a problem of lowering production efficiency. Further, since a steel cord or the like is used for the reinforcing cord, there is a problem that the material recyclability cannot be sufficiently improved.

The present invention is based on the fact that the tread reinforcing element is made of a thermoplastic resin and the formation position of the tread reinforcing element is regulated, and the production efficiency is improved while ensuring the stability of the ground contact shape of the tire. The challenge is to provide pneumatic tires that can improve material recyclability.

The present invention is a pneumatic tire.
Includes tread reinforcement elements located between the tire lumen surface and the tire tread surface
The tread reinforcing element is made of a thermoplastic resin and is made of a thermoplastic resin.
On any reference line across the tread reinforcement element and parallel to the tire equator.
The thickness center point of the tread reinforcing element is such that the distance L1 in the tire radial direction from the tire inner surface is 50 to 95% of the tire radial distance L0 from the tire inner surface to the tire contact patch. The range.

The pneumatic tire according to the present invention includes a toroid-shaped tire skeleton member including a pair of bead portions, a pair of sidewall portions, and an under tread portion connecting the pair of sidewall portions.
It is preferable that the inner surface of the under tread portion in the radial direction of the tire forms the inner surface of the tire, and the tread reinforcing element is arranged on the outer surface in the radial direction of the tire.

In the pneumatic tire according to the present invention, the tire skeleton member is preferably made of the same or a plurality of types of thermoplastic resins.

In the pneumatic tire according to the present invention, the tread ground contact element forming the tire ground contact surface is provided on the outer side of the tread reinforcing element in the tire radial direction, and the tread ground contact element is a tread ground contact element.
It is preferably made of vulcanized rubber or thermoplastic resin.

In the pneumatic tire according to the present invention, the thermoplastic resin forming the tread reinforcing element preferably has a tensile elastic modulus of 1000 MPa or more.

In the pneumatic tire according to the present invention, the thermoplastic resin forming the tire skeleton member preferably has a tensile elastic modulus of 30 to 200 MPa or less.

In the pneumatic tire according to the present invention, it is preferable that the tread reinforcing element contains a fibrous filler in the thermoplastic resin.

In the pneumatic tire according to the present invention, the filler is preferably oriented in the tire circumferential direction.

In the pneumatic tire of the present invention, the tread reinforcing element is made of a thermoplastic resin. This eliminates the need for a process of winding the reinforcing cord, and can improve the production efficiency while improving the material recyclability.

In addition, when the tread reinforcing element is made of thermoplastic resin, the binding force is inferior to that when a reinforcing cord such as a steel cord is used, so that the stability of the ground contact shape of the tire is reduced and the running performance is adversely affected. Invite a tendency. On the other hand, in the present invention, the distance L1 in the tire radial direction from the tire internal surface of the thickness center point of the tread reinforcing element is the distance L0 in the tire radial direction from the tire internal surface to the tire contact patch. It is regulated in the range of 50 to 95%. That is, the tread reinforcing element is arranged near the tire contact patch.

As a result, while the tread reinforcing element is formed of the thermoplastic resin, the stability of the ground contact shape of the tire can be ensured, and the adverse effect on the running performance can be suppressed to a low level.

It is sectional drawing which shows one Example of the pneumatic tire of this invention. It is sectional drawing which shows the bead part enlarged. It is sectional drawing which shows the tread part enlarged together with the tread reinforcing element. (A) to (c) are conceptual diagrams showing a method of manufacturing a pneumatic tire.

Hereinafter, embodiments of the present invention will be described in detail.
As shown in FIG. 1, the pneumatic tire 1 of the present embodiment (hereinafter, may be simply referred to as a tire 1) has a tread reinforcing element 4 arranged between a tire cavity surface 1H and a tire contact patch 1S. The tread reinforcing element 4 is made of a thermoplastic resin.

Specifically, the tire 1 of this example includes a tread-shaped tire skeleton member 2 having a tire cavity surface 1H, a tread ground contact element 3 having a tire ground contact surface 1S, and an undertread portion 7 of the tire skeleton member 2. It includes a tread reinforcing element 4 arranged between the tread grounding element 3 and the tread ground element 3.

In this example, the case where the tire 1 is a tire for a passenger car is shown. However, the present invention is not limited to this, and can be adopted for tires of various categories such as for motorcycles, light trucks, and heavy-duty trucks.

The tire skeleton member 2 includes a pair of bead portions 5, a pair of sidewall portions 6 extending outward in the radial direction of the tire from the pair of bead portions 5, and an under tread portion 7 connecting the pair of sidewall portions 6. The inner surface of the under tread portion 7 in the radial direction of the tire forms the tire lumen surface 1H.

The bead portion 5 is a portion that fits into the rim R when the rim is assembled. The sidewall portion 6 is a portion constituting the side portion of the tire 1, and extends outward in the radial direction of the tire while being curved in an arc shape that is convex toward the outside in the tire axial direction. The under tread portion 7 is a portion that supports the tread ground contact element 3, and connects between the tire radial outer ends of the sidewall portion 6.

The tire skeleton member 2 is made of the same or a plurality of types of thermoplastic resins. The fact that the tire skeleton member 2 is made of the same thermoplastic resin means that the bead portion 5, the sidewall portion 6, and the under tread portion 7 are made of the same thermoplastic resin. Further, being composed of a plurality of types of thermoplastic resins means that, for example, the bead portion 5, the sidewall portion 6, and the under tread portion 7 are composed of different thermoplastic resins.

In this example, the pair of sidewall portions 6 and the under tread portion 7 are composed of the second thermoplastic resin M2. Further, a case where the pair of bead portions 5 is composed of the third thermoplastic resin M3 is shown.

In other words, the tire skeleton member 2 includes a first substrate 8A made of a second thermoplastic resin M2 and a second substrate 8B made of a third thermoplastic resin M3. Then, the first substrate 8A forms a pair of sidewall portions 6 and an under tread portion 7. Further, the second substrate 8B forms a pair of bead portions 5.

As shown in FIG. 2, the boundary surface K between the first base 8A and the second base 8B is inclined with respect to the tire axial direction line, that is, the bonding strength between the first base 8A and the second base 8B. It is preferable to increase the amount of tires. In particular, it is preferable that the intersection Po of the outer surface of the tire skeleton member 2 and the boundary surface K is located inside the intersection Pi of the inner surface of the tire skeleton member 2 and the boundary surface K in the radial direction of the tire. As a result, the exposed area of the outer surface of the second substrate 8B is reduced, which helps to suppress damage such as cracks due to tire deformation.

The height hb of the intersection Po in the tire radial direction from the bead baseline BL is preferably in the range of 1.0 to 3.0 times the rim flange height hf. If it is less than 1.0 times, it becomes difficult to sufficiently improve the steering stability. On the contrary, if it exceeds 3.0 times, the effect of suppressing damage such as cracks is reduced, and the riding comfort performance is disadvantageous. The rim flange height hf is defined as the height of the top of the rim flange Rf in the tire radial direction from the bead baseline BL.

In this example, an annular bead core 10 is arranged in the second substrate 8B in order to increase the fitting force with the rim R. As the bead core 10, a tape bead structure and a single wind structure can be appropriately adopted. In the tape bead structure, an array of bead wires aligned in parallel with each other is spirally wound from the inside to the outside in the radial direction in a strip shape topped with rubber or a thermoplastic resin, whereby the bead core 10 is formed. .. In the single wind structure, one bead wire is continuously wound in a spiral and multi-row multi-stage, whereby the bead core 10 is formed. As the bead wire, a steel cord is preferably adopted, but an organic fiber cord may also be adopted. The bead core 10 can also be excluded depending on the tire category and the like.

As shown in FIG. 1, the tread reinforcing element 4 is arranged on the outer surface of the under tread portion 7 in the radial direction of the tire. Further, the tread ground contact element 3 is arranged on the outer side of the tread reinforcing element 4 in the radial direction of the tire.

The tread ground contact element 3 is a portion that comes into contact with the road surface, and the outer surface in the radial direction of the tire forms the tire ground contact surface 1S. Tread grooves 9 for enhancing wet performance are formed on the tire contact patch 1S in various patterns.

The tread grounding element 3 can be formed of vulcanized rubber or a thermoplastic resin. However, from the viewpoint of enhancing material recyclability, it is preferable to form the tread grounding element 3 with a thermoplastic resin.

When a thermoplastic resin is used for the tread ground element 3, the tread ground element 3 has a tensile modulus E1 smaller than the tensile modulus E2 and E3 of the second and third thermoplastic resins M2 and M3, respectively. It is preferable to use the first thermoplastic resin M1 from the viewpoint of improving the followability to the road surface and improving the grip.

The tensile elastic moduli E2 and E3 are preferably in the range of 30 to 200 MPa, and if it is less than 30 MPa, the rigidity of the tire skeleton member 2 itself becomes insufficient, and it becomes difficult to secure steering stability. On the contrary, if it exceeds 200 MPa, the vertical rigidity of the tire becomes excessive and the ride quality deteriorates. It is more preferable that E2 <E3 from the viewpoint of achieving both steering stability and ride quality. The tensile elastic modulus is a value measured according to the test method described in "Plastic-How to determine tensile properties" of JIS K7161.

As shown in FIG. 3, the tread reinforcing element 4 is made of a thermoplastic resin, and in this example, a resin reinforcing layer made of a fourth thermoplastic resin M4 different from the first to third thermoplastic resins M1 to M3. Formed as 15.

The tensile elastic modulus E4 of the fourth thermoplastic resin M4 is larger than the tensile elastic moduli E1 to E3. In the tread reinforcing element 4, the under tread portion 7 is restrained by the tag effect to stabilize the ground contact shape of the tire. Therefore, the tensile elastic modulus E4 of the fourth thermoplastic resin M4 is preferably 1000 MPa or more, more preferably 2000 MPa or more. Further, from the viewpoint of suppressing damage, the tensile strength of the fourth thermoplastic resin M4 is preferably 200 MPa or more.

In order to enhance the tagging effect of the tread reinforcing element 4, it is preferable to include a fibrous filler in the fourth thermoplastic resin M4, and it is more preferable to orient the filler in the tire circumferential direction.

Suitable fillers include carbon fibers, glass fibers, aramid fibers, cellulose nanofibers (CNF), cellulose nanocrystals (CNC) and the like, which can be used alone or in combination.

Even when such a fourth thermoplastic resin M4 is used, the stability of the ground contact shape of the tire is reduced as compared with the case where the tread reinforcing element is formed by a reinforcing cord such as a steel cord, which adversely affects the running performance. Invites a tendency to give.

Therefore, the tread reinforcing element 4 is arranged closer to the tire contact patch 1S. Specifically, as shown in FIG. 3, the following requirements are satisfied on an arbitrary reference line X extending in parallel with the tire equator C across the tread reinforcing element 4.

That is, on the reference line X, the distance L1 in the tire radial direction from the tire internal surface 1H to the thickness center point 4P of the tread reinforcing element 4 is the tire radial direction from the tire internal surface 1H to the tire contact patch 1S. The distance is in the range of 50 to 95% of L0.

With such a configuration, the thickness of the under tread portion 7 is increased, and the under tread portion 7 is restrained at a position close to the tire contact patch 1S. As a result, the stability of the ground contact shape of the tire can be ensured, and the running performance, particularly the steering stability, can be maintained high. If the distance L1 is less than 50% of the distance L0, the effect of ensuring the stability of the ground contact shape is not sufficiently exhibited. On the contrary, if it exceeds 95%, it becomes difficult to form the tread groove 9 and secure the wear life. From such a viewpoint, the lower limit of the distance L1 is preferably 55% or more of the distance L0, and the upper limit is preferably 70% or less.

It is also preferable that the value of the ratio L1 / L0 gradually increases from the tire equator C toward the outside in the tire axial direction.

In the present application, the "thermoplastic resin" includes a thermoplastic elastomer. The "thermoplastic resin" means a polymer compound in which a material softens and flows as the temperature rises, and when cooled, it becomes relatively hard and strong. The "thermoplastic elastomer" has the characteristics that the material softens and flows as the temperature rises, becomes relatively hard and strong when cooled, and has rubber-like elasticity.

Considering the elasticity required during running, moldability during manufacturing, etc., a thermoplastic elastomer is preferably used for the tire frame member 2 and the tread grounding element 3, and rubber-like elasticity is used for the tread reinforcing element 4. A thermoplastic resin that does not exist is preferably used.

Examples of the thermoplastic elastomer include polyamide-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, and polyolefin-based thermoplastic elastomers, which may be used alone or in combination. sell.

Next, an example of the manufacturing method of the tire 1 of the embodiment will be shown. As conceptually shown in FIGS. 4A to 4C, the manufacturing method of this example is
Step S1 for forming the first tire base 1A in which the under tread portion 7, the tread reinforcing element 4, and the tread ground contact element 3 are integrated,
Step S2 for forming a pair of second tire bases 1B in which the sidewall portion 6, the bead portion 5, and the bead core 10 are integrated,
A step S3 of joining the first tire base 1A and the second tire base 1B to form the tire 1 is included.

In step S1, the first tire base 1A is formed by injecting a first thermoplastic resin M1, a second thermoplastic resin M2, and a fourth thermoplastic resin M4 into the cavity. Form.

In step S2, after the bead core 10 is formed in advance, a composite molding is performed in which the second thermoplastic resin M2 and the third thermoplastic resin M3 are injected into the cavity in which the bead core 10 is set. The second tire base 1B is formed.

In step S3, the first tire base 1A and the second tire base 1B are joined by heat fusion or using an adhesive. As the adhesive, for example, Aron Alpha EXTRA2000 (registered trademark) manufactured by Toagosei Co., Ltd., Loctite 401J (registered trademark) manufactured by Henkel Japan Ltd., and the like can be preferably used.

Although the particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified into various embodiments.

In order to confirm the effect of the present invention, the contact width and productivity of a passenger car tire (195 / 65R15) having the structure shown in FIG. 1 were estimated when they were prototyped based on the specifications in Table 1. ..

Comparative Example 1 has substantially the same configuration as that of the embodiment except that the tread reinforcing element is a cord reinforcing layer in which a steel cord is spirally wound. In the comparative example and the embodiment, the contour shapes of the tire cross sections are the same as each other before the internal pressure air filling. Further, in the embodiment, a feeler made of glass fiber is blended in the tread reinforcing element.

<Grounding width>
By simulation by the finite element method, the tire shaft of the ground contact surface when the tire is grounded vertically to the road surface under the conditions of regular rim (15 x 6JJ), regular internal pressure (230kPa), and regular load (3.43kN). The width in the direction (ground contact width) was calculated. The results are expressed as an exponent with Comparative Example 1 as 10. The larger the value, the better the stability of the ground contact shape.

<Productivity>
Tire productivity is expressed as an index with Comparative Example 1 as 10. The larger the number, the better the productivity.

The thermoplastic resins used in Table 1 are shown in Table 2.

As shown in Table 1, it can be confirmed that the examples can improve the production efficiency while ensuring the stability of the ground contact shape. By forming the tread reinforcing element with a thermoplastic resin, it can contribute to the improvement of material recyclability.

1 Pneumatic tire 1H Tire tread surface 1S Tire ground contact surface 2 Tire skeleton member 3 Tread ground contact element 4 Tread reinforcement element 4P Center point 5 Bead part 6 Side wall part 7 Under tread part C Tire equatorial X reference line

Claims (8)

Pneumatic tires
A tread shape including a tread reinforcing element arranged between a tire lumen surface and a tire contact patch, a pair of bead portions, a pair of sidewall portions, and an under tread portion connecting the pair of sidewall portions. Including tire skeleton members
The tread reinforcing element is made of a thermoplastic resin and is made of a thermoplastic resin.
The distance L1 in the tire radial direction from the tire internal surface to the thickness center point of the tread reinforcing element is the distance L1 from the tire internal surface to the tire internal surface on an arbitrary reference line that crosses the tread reinforcing element and is parallel to the tire equatorial line. The distance in the tire radial direction to the tire contact patch is in the range of 50 to 95% of L0 .
The tire skeleton member is a pneumatic tire made of the same or a plurality of types of thermoplastic resins .
The pneumatic tire according to claim 1, wherein the inner surface of the under tread portion in the radial direction of the tire forms the inner surface of the tire, and the tread reinforcing element is arranged on the outer surface in the radial direction of the tire.
The pneumatic tire according to claim 1 or 2, further comprising a tread ground contact element forming the tire ground contact surface on the outer side of the tread reinforcing element in the tire radial direction .
The pneumatic tire according to claim 3 , wherein the tread grounding element is made of vulcanized rubber or a thermoplastic resin.
The pneumatic tire according to any one of claims 1 to 4, wherein the thermoplastic resin forming the tread reinforcing element has a tensile elastic modulus of 1000 MPa or more. The pneumatic tire according to any one of claims 1 to 5 , wherein the thermoplastic resin forming the tire skeleton member has a tensile elastic modulus of 30 to 200 MPa or less.
The pneumatic tire according to any one of claims 1 to 6, wherein the tread reinforcing element contains a fibrous filler in the thermoplastic resin. The pneumatic tire according to claim 7, wherein the filler is oriented in the tire circumferential direction.

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